This invention relates generally to a refrigerator, and more particularly, to evaporators and airflow in a refrigerator.
A known refrigerator typically includes at least one evaporator and one or more plenums to circulate air chilled by an evaporator in a compartment of the refrigerator. The evaporator is connected to a compressor to circulate a cooling medium between a condenser and the evaporator. The refrigerator often contains a freezer compartment, a fresh food compartment or both. The freezer compartment is used to store food and other items at temperatures below zero degrees Celsius while the fresh food compartment is used to store foods and other items at temperatures above zero degrees Celsius.
In one type of known refrigerator, a freezer compartment is located above a fresh food compartment. In this configuration, a single evaporator is used and a baffle is placed in a plenum operatively connecting the freezer compartment and the fresh food compartment of the refrigerator. The single evaporator is used to cool the freezer compartment with chilled air to the desired temperature. The baffle is used to control the flow of chilled air to the fresh food compartment to maintain the desired temperature in that compartment. This may be chilled air directed from the freezer compartment, chilled air directed from the evaporator, or a combination.
Another type of known refrigerator is a so-called side-by-side refrigerator that includes a freezer compartment disposed to the side of a fresh food compartment. FIG. 1 is a front perspective view of such a side-by-side refrigerator 200, which may include a fresh food compartment (shown in FIG. 4 as 201) having an interior volume that is cooled to a temperature greater than a standard freezing point temperature of water (e.g., greater than 0 degrees Celsius). The refrigerator 200 also may include a freezer compartment (shown in FIG. 4 as 203) having an interior volume that is cooled to a temperature equal to or less than the standard freezing point temperature of water. Doors 205 and 208 are used to permit and impede or prevent access to the interior volume of the fresh food and/or freezer compartments, respectively. In this design, often two evaporators, one in each compartment, are used to permit individual control of the temperature in each of the controlled compartments. FIG. 2 is a side cross-sectional view of a chilled air system of a freezer compartment of a refrigerator of FIG. 1. Specifically, as shown in FIG. 2, a freezer compartment 303 of the side-by-side refrigerator includes baskets 320 and shelves 322 for holding food items. Air flow 302 is created by fan 304, which draws air from the bottom of the compartment 303 at 306 and into a plenum 324 running to the upper part of the compartment 303. The air is drawn over or through evaporator 308 chilling and dehumidifying the air. The chilled air is then returned to freezer compartment 303 at outlet 307 where some of the chilled air is diverted over icemaker 312 or ice reservoir 316. The rest of the chilled air is returned directly to the freezer compartment 303. The removal of air from the bottom of freezer compartment 303 at 306 and return of chilled air at the top of freezer compartment 303 at outlet 307 creates a generally circular flow 310 encompassing the entire cavity of the freezer compartment 303. This method decreases the temperature gradient within the freezer compartment 303 by discharging chilled air at the top of the compartment to mix with the warmer air. However, this design has not eliminated temperature gradients because obstructions to the circulation of air in the compartment exist and because this design still allows the settling of air during non-cooling periods. Further, when utilized in the fresh food compartment, insulation is needed around the plenum to prevent condensation buildup due to the temperature differential between the cold air in the plenum prior to discharge and the warmer air at the top of the compartment, which may cause frost buildup around the opening of the plenum.
This design also requires the air to travel most of the height of the compartment within the confines of the plenum as the air flows around, through or over the evaporator. To provide the airflow volume necessary to maintain the chilled temperature in the compartment this design requires considerable system pressure and the evaporator must be doubled over to ensure sufficient channels of flow. This reduces the useful volume of the compartment. Further, a larger fan motor is necessary to maintain the higher system pressure due to the distance traveled by the air in the plenum. Using a larger fan motor creates more noise and is less efficient than using a smaller fan motor.